In vehicle engineering, various conventional systems reduce the risk of injury to vehicle passengers during an accident. For example,                the closing of side windows,        the closing of the sunroof,        straightening of the seat or        tightening of the seat belts.        
With the last two measures named, the driver is maneuvered into an upright position to thereby reduce the intensity of head movements. However, the tightening of the seat belt no longer makes sense if the driver has already been thrown too far forward due to an accident. For optimal functioning of the seat-belt tightener, the system must react with appropriate speed. The system must not be activated too quickly, however, since any activation of the seat-belt tightener means a loss of comfort. After the critical phase has ended, a loosen signal is sent to the seat-belt tightener.
German Patent Application No. DE 101 21 386 describes a method for triggering a reversible passenger protection means in a motor vehicle having a driving-condition sensor system. The reversible passenger protection means can be triggered prior to the moment of collision and thereby be brought into active setting. To that end, the driving-condition data are monitored with respect to an emergency-braking state, and the passenger protection system is triggered in response to ascertainment of the emergency-braking state. In addition, an understeering state and an oversteering state are ascertained by the data-processing device. The reversible passenger protection system is triggered when the emergency-braking state and/or the oversteering state and/or the understeering state is detected by the data-processing device.